Hydromechanical gauge control system for a rolling mill and like device



April 1, 1969 HYDROMECHA CAL A B0 NG Filed y 4. 1967 W- O'BRIEN GAUGE CONTROL MILL AND LIKE D SYSTEM FOR EVICE Sheet I of 4 Fig.1

A TTORNEY.

A ril 1, 1969 J. OBRVIEN 3,435,649

HYDROMECHANICAL GAUGE CONTROL SYSTEM FOR A ROLLING MILL AND LIKE DEVICE Filed may 4. 1967 AME Sheet 2 014 M44 sm/P mam o/Aencrse/srxcs MM (we/swamp) VVVV x INVENTPR.

JfPE/MMH 14/. 052/5 ATTORNEY.

IEN NT April 1, 1969 J. w. O'BR 3,435,649

HYDROMECHANICAL GAUGE CO ROL SYSTEM FOR A ROLLING MILL AND LIKE DEVICE Sheet 3 014 Filed May 4. 1967 A TTORIVEY.

April 1, 1969 J. w. OBRIEN 3,435,649 HYDROMECHANICAL GAUGE CONTROL SYSTEM FOR A ROLLING MILL AND LIKE DEVICE Filed May 4. 1967 Sheet 4 of 4- INVEN'EOR. JEREMIAH W OER/EN ATTOR/VEK United States Patent US. CI. 72-19 4 Claims ABSTRACT OF THE DISCLOSURE A rolling mill including a pair of piston cylinder assemblies arranged at the top of the mill housing for urging the upper roll in a direction to oppose the rolling force and at a force greater than the rolling force. Around each cylinder is a hollow sleeve which is splined so that while the sleeves cannot rotate they are allowed to move vertically to set the initial gap of the mill. The sleeves are driven by a motor-worm wheel set. Between the sleeves and the pistons of the cylinders springs are located which resist the downward movement of the piston.

CROSS REFERENCE TO RELATED APPLICATION This application is based on a British Provisional, Ser. No. 40,489/66, dated Sept. 9, 1966, for which application the applicant is claiming a right of priority pursuant to 35 U.S.C. 119 of the Patent Act.

BACKGROUND OF INVENTION Because of the change in the elastic stress of the components of the mill when subject to rolling force, it has been heretofore extremely difl icult, although repeated attempts have been made, to construct a mill and/or roll gap control system that would assure the commercial production of constant gauge material. Some of the prior United States patents that attempted to obtain this result are as follows:

Melber, 304,342, Sept. 2, 1884; Menne, 581,078, Apr. 20, 1897; Biggert, 1,980,570, Nov. 13, 1934; Shayne et al., 2,339,359, Jan. 18 1944; Hessenberg et al. 2,680,- 978, June 15, 1954; Blain, 2,736,217, Feb. 28 1956; Warren et al., 3,024,680, Mar. 13 1962; Neumann 3,124,982, Mar. 17, 1964; Cozzo, 3,247,697, Apr. 26, 1966.

The mill structure illustrated in these patents and the controls disclosed in connection therewith are subject to some very serious technological deficiencies and practical limitations. Several are objectionable because the gauge control system is subject to a lag time between the time the error in gauge is detected and a correction in roll gap is effected. US. Patent Nos. 2,339,359 and 2,680,978 are exemplary of such mills. Other mill designs of the prior art patents fail to compensate for the stretch of all of the major components of the mill, whereby the gauge varies from what is desired by the amount of the stretch of the parts not compensated for. US. Patents Nos. 1,980,570 and 3,247,697 are illustrations of mills of this type.

All of the prior art patents, in addition, involve considerable additional expense in the manufacture, operation and maintenance of the mill, such as complicated housing and chock designs, elaborate and complex control systems and interference with the quick replacement of the rolls of the mill. Such mills are exemplified by US. Patents Nos. 1,980,570; 2,736,217 and 3,247,697.

SUMMARY OF INVENTION The present invention relates to an improved rolling mill and like device, including an automatic gauge control system therefor which overcomes the limitations and objections to the prior art noted above and, in a manner that will in nowise create a limitation or deterrent with respect to the cost, operation and maintenance of the mill. More particularly, a mill built in accordance with the present invention will require no significant departure from the present well-accepted housing, and roll chock designs, nor will it in any way encumber the ability to quickly change the rolls of the mill whether work rolls or backup rolls.

One of the primary features of the present invention is to provide in a mill a compact, yet single, roll positioning device capable of both adjusting the initial gap of the rolls and automatically controlling the roll gap in a manner that will assure the obtaining of uniform longitudinal gauge, and which will possess the highly soughtafter characteristics of low manufacturing, operating and maintenance costs. In addition, the roll positioning device allows the mill to be operated as a pressure rolling mill.

The present invention contemplates providing in a rolling mill or like device having a housing for receiving a pair of cooperative rolls between which material to be rolled is passed, roll mounting means for rotatably supporting the rolls in said housing, one mounting means being at least adjustable relative to the other so that said rolls form a roll gap, a force applier adapted to urge the adjustable roll in a direction opposite the rolling force developed between the rolls, an opening in said housing through which a portion of the force applier extends to assume a restricting relationship with the mounting means of the adjustable roll, a member arranged in said opening concentric with the extended portion of said force applier for limiting movement thereof and thereby establishing a desired position of the adjustable roll, means separate from said force applier for adjusting said member, yieldable means associated with said member and constructed and arranged to allow additional movement of said adjustable roll on operation of said force applier.

The above-described mill is adapted to function with a control system including means for producing a signal proportionate to a change in the rolling force and means for varying the force exerted by said force applier so that the force thereof will always be equal to the algebraic sum of the rolling force and the force of said yieldable means.

It is a feature of the present invention that the elastic characteristic of a first group of mill parts which comprise certain parts of the above-described roll positioning mechanism, including the readily yieldable member and the elastic characteristic of a second group of mill parts comprising the housing and chocks and rolls, will be such that for a given elastic change of the second group of mill parts due to a change in the rolling force a corresponding elastic change will be effected in the first group of mill parts, but in a direction to compensate for the elastic change of the second group thereof.

It is another feature of the present invention that the above-described roll positioning mechanism is so constructed that the member adapted to limit movement of the force applier and the means for adjusting said member are subject only to the difference between the rolling force and the force applied by said force applier.

Before referring to the drawings, it is to be appreciated that, while for purposes of illustration the applicant has selected one form of his invention, the principles of the invention may be utilized in other forms. Moreover, it will be readily appreciated that the roll positioning and gap control mechanism illustrated in FIGURE 1, as related to the top of the mill, can just as well be employed at the bottom of the mill and that the mechanism may be employed with 2- and 4-high mills as well as other multi-high rolling mills.

DRAWINGS OF INVENTION The above features and advantages as well as others will be more evident from the following description read along with the accompanying drawings of which:

FIGURE 1 is a elevational view, partly in section, of the upper portion of a rolling mill stand incorporating what presently is the preferred embodiment,

FIGURE 2 is a diagrammatically illustrated control circuit for use in connection with the illustrated form in FIGURE 1,

FIGURES 3a and 3b are a second embodiment of the roll positioning mechanism of the present invention,

FIGURE 4 is a third embodiment of the roll positioning mechanism of the present invention, and

FIGURE 5 is a sectional view taken on lines VV of FIGURE 4.

DESCRIPTION OF INVENTION In referring now to FIGURE 1, there is illustrated the upper portion of the conventionally constructed housing 11 having a window 12 into which there is received a backup chock 13 for rotatably supporting within the housing 11 a backup roll 14. While not shown, since such is well known in the art, the backup roll 14 is designed to engage a cooperative work roll which forms a roll gap with a lower Work roll which is backed up by a second backup roll. The construction of these unillustrated mill components, as well as other standard mill components not mentioned, are amply illustrated in the aforesaid prior art patents. The rolls will be urged apart by balance cylinder assemblies in the usual manner.

As noted above, the present invention is addressed to an improved roll positioning mechanism having the advantage of not only being very compactly constructed, but eliminates any need of complicating the design of the other components of the mill, in addition to avoiding any complications or restrictions in changing of the rolls. In this regard it will be noted that the roll positioning means to be discussed is arranged at the top of the housing 11, in such a manner as to allow quick removal of the rolls of the mill and without necessitating any elaborate or extravagant changes in the mill components, such as chocks thereof.

In returning again to FIGURE 1, which illustrates one of the identical housings, it will be noted that the position of the backu roll 14 and, hence, its work roll is controlled by a plunger rod 16, the lower end of which is separated from the top of the chock 13 by a combined pressure block and load cell assembly, the load cell being identified by the reference numeral 17 and the pressure block by the reference numeral 18, both of which are contained within an outer casing 19 carried between the top of the backup chock 13.

The plunger rod 16 at the upper end thereof is formed as an integral part of a piston 22 received in a cylinder 23, the cylinder being connected to a frame 24, the lower end of the frame 24 being secured to the top of the housing 11 by a relatively large lock nut 25. While not shown, it will be appreciated that the piston cylinder assembly is a one directional cylinder, in which pressure is applied to the top of the piston 22 to force the plunger rod 16 downward against the chock 13 and, as will be noted hereinafter, with a pressure slightly greater than the rolling force of the mill, say, in the order of 5 to 10 percent. The piston cylinder assembly will be supplied with pressurized fluid from a variable pressure pump of a type well known, as exemplified by several of the above-mentioned patents.

Concentric with the plunger rod 16 and extending from the top of the window 12 to the bottom portion of the piston 22 is a vertically displaceable sleeve 26. The sleeve 26 is prevented from rotating by spline connection at the bottom of sleeve 26 and frame 24. As noted, the sleeve is received in the frame 24 and is adapted to extend into the cylinder 23, the frame 24 being provided with a recess towards the top of the sleeve for the reception of a worm wheel 27 to which the sleeve is connected. The worm wheel 27 is rotatably mounted in the frame by virtue of bearings 28 and rotates about the vertical axis of the plunger rod 16, being driven by a worm 29; the worm, in turn, being driven by an electric motor not shown. The worm is rotatably mounted in hearings in the frame 24. On rotations of the wheel 27, the sleeve 26 is caused to move vertically, the two extreme positions of which are illustrated on the left and right-hand sides, respectively, of FIGURE 1.

Addressing attention now to the top of the sleeve 26, it will be noted that both it and the opposed surface of the piston 22 are provided with opposed wear plates 32 and 33, respectively, between which there is arranged a compressible spring 34. The opening between the plates 32 and 33 allows the plates to serve as stop members which prevent the spring from being subject to abnormal force above the design limitation of the spring. As noted previously, the sleeve 26 serves to restrict the movement of the piston 22 and, hence, the plunger rod 16 in a downward direction, subject, however, to the degree of compressibility of the spring. The spring illustrated is designed to permit adjustment of the roll gap by an amount of .080 inch and designed to withstand total forces of the order of 200,000 lbs.

It should also be noted that with respect to the application of the rolling force and the force of the piston cylinder assembly that the sleeve 26, worm wheel 27 and worm 29 are subject only to the ditference between the cylinder force and the rolling force, thereby the torque necessary to effect movement of the sleeve and, hence, a positioning of the roll 14 and its work roll, need only work against the aforesaid differential pressure. This allows a considerable reduction in the motor capacity of the screwdown. At this point it should also be noted that, even in a mill provided with a backup crown control, for example, as illustrated in US. Patent No. 3,250,105 issued May :10, 1966, the reaction force of which will be taken by the plunger 16, the presssure of the cylinder 23 can be made to offset this reaction force so that, even in this case, the sleeve 26 and worm wheel 27 and worm 29 is only subject to the differential between the pressure of the cylinder and the rolling force.

As noted previously, in addition to the roll positioning device being employed for automatic gap control of the mill, it also allows the mill to be used as a pressure rolling mill. In this case the cylinder pressure is held constant and the material is subject to a constant rolling force, which is a type of rolling advantageously employed in rolling aluminum lfOiI. When it is desired to use the mill as a pressure rolling mill, the sleeve is lowered so that the piston 22 does not transfer its pressure to the spring 34 and, hence, to the sleeve 26.

It is one of the features of the present invention to provide a control whereby the roll positioning mechanism described above can be operated to provide for the automatic and continous adjustment of the roll gap of the mill, which will have the advantage of being very rapid in correcting for detected error gua-ge in the thickness of the material.

In order to obtain automatic gap control, the present invention is provided with a structure wherein the force of the piston cylinder assembly 2 3 is controlled by the formula:

where, F equals the cylinder force, Y equals the proportionality of the modulus or elastic coefiicient of the spring 34 and the elastic coefiicient of the mill, including the housing 11, and P is the rolling force.

This formula is derived from the following considerations:

in the illustrated mill, since the cylinder force F is always greater than the rolling force P, the difference between these two forces (FP) will be conducted from the piston 22 through the spring 34 into the worm wheel 23 and wonm 29 into the nut 25 and the lower roll bearing and, consequently, into the mill housing. Let the modulus of the spring 34 and sleeve 26 be designated M the modulus of the mill housing, the chocks, rolls, etc. as M Now it is the object of the control system to vary the force of the piston cylinder assembly 23 with regard to the rolling force so that elastic changes due to a change in the rolling force which cen be represented as AP/M may be compensated for by offsetting changes in the elastic characteristics of the screwdown parts, primarily the spring 34, although the sleeve 26 may be made to be a significant factor, which can be represented as AF-A-P/M This compensating feature, which according to the present invention will be performed automatically, will become manifest from the following:

Let S equal the elastic change of the mill as related to the roll :galp;

Let Y equal the ratio of the modulus of the spring over the modulus of the mill; thus the conditions can be established for maintaining the gap constant by equating Equation No. 4 to equal zero. Thus,

ZAE L M S M s M 5 (Equation No. 5) which in terms for solving for AF can be written as AF=-(Y+l)AP (Equation No. 6)

In solving for F, for required pressure of the cylinder 23, the following is derived:

(Equation No. 7) in the preferred design the flexible elements, such as the sleeve 26 and the spring 34 will be designed sothat Y is approximately .2; thus F=-l.2P.

While the control of the cylinder force F can be obtained by a number of control systems, a very satisfactory one is illustrated in FIGURE 2.

With reference to FIGURE 2, which illustrates a control for practicing the invention, as noted above, it is the object of the control to produce a signal representing the required change in the cylinder pressure according to the formula: F=(Y+1)P. Accordingly, in FIGURE 2 there is provided a potentiometer 38 which is manually adjusted to produce a signal representing the quantity M of Equation No. l which is sent to a summation amplifier 39, the summation amplifier '39 also receives signals from potentiometers 41 and 42 representing certain variable elastic characteristics of the roll and strip, such as, in the first case, change in size of the roll diameters and, in the second, strip width which influence the stretch of the mill. The amplifier 39 produces a modified signal representing the corrected value for the M quantity which is received by a dividing amplifier 43. This amplifier 43 also receives from a manually adjustable potentiometer 44 a signal representing the quantity M of Equation No. 1.

As indicated in FIGURE 2, the dividing amplifier 43 produces a signal representing Y which, as previously noted, equals M /M and sends the signal to a dividing amplifier 44a. The dividing amplifier 44a also receives a signal from a manually operated potentiometer 45, the signal representing a value V. The signal from the amplifier 44a which is represented by a quantity Y/ V is sent to an amplifier 46. This amplifier receives from a secondary amplifier 47 a quantity 1/ V, it being noted that the amplifier 47 receives a signal representing the quantity V from the potentiometer 45. Hence, the amplifier 46 adds the values signal equalling the value Y+1 from the input signals representing It should be noted that there are other ways to establish Y+l and feed its signal into the system. Thus, the amplifiers 3948 are employed to produce the quantity of Equation No. 7: Y+l, which signal is sent from the amplifier 48 to a summation amplifier 49. This amplifier also receives a second signal representing the rolling force P.

As noted in the lower part of FIGURE 2, the load cell 17 sends a signal to a secondary amplifier S1 and also sends a signal to an amplifier 52 which receives a second signal from a manually operated potentiometer 53. The amplifier 52 sends its signal to a relay 54 which has a normally open contact and a normally closed contact, 54a and 54b, respectively, as shown. The potentiometer 56 produces a signal representing V so that in the event that the value P is zero or below a predetermined pressure then the signal V represents the force of P. Relay 54 applies either the P or V signal to the amplifier 52, depending on the output from the load cell. Accordingly, the amplifier 51 produces a signal; either P or V and sends its signal to the amplifier 49. The amplifier 49 produces a signal normally representing P(Y+l), which is sent to a solenoid 57 which operates a valve 58 that controls the pressure in the piston cylinder assembly 23 arranged at the bottom of the housing 11.

It will be appreciated that the various amplifiers illustrated in FIGURE 2 are of the typical, well-known de sign as exemplified in a publication by Korn and Korn, entitled Electric Analog Computers, published by Mc- Graw-Hill, 1952.

In operation the values of the various manual potentiometers, such as, 38, 41, 42, 44, 45, 53, and 56 will be predetermined and the load cell 17 will produce a signal proportional to the actual rolling force of the mill so that the pressure of the cylinder 23 which is represented by the quantity F of Equation No. 7 will be changed pursuant to the change in the rolling force an amount necessary to compensate for any change in the effective length of the mill parts represented by the Y quantity.

Reference will now be made to FIGURE 3 which, as noted previously, illustrates a second embodiment of the roll positioning mechanism illustrated in FIGURE 1. It will be appreciated that various constructions are possible with respect to the location of the spring in relationship to the plunger rod 16 and sleeve 23. The important consideration being that the spring be arranged intermediate the plunger and the sleeve for the transmission of force from one to the other.

It will be observed in comparing FIGURE 3 with FIGURE 1 that the upper portion of the roll positioning mechanism is very similar and that the major difference in the embodiments have reference to the lower portion of the mechanism illustrated in FIGURE 1. Thus, in FIGURE 3 the lower portion of the plunger 16a is provided with an enlarged collar 61 whereas the sleeve 26a in the same region is provided with an enlarged portion 62 having an opening 63 for receiving the collar 61 of the plunger rod 16a. The lower portion of the sleeve and, particularly, the enlarged portion thereof is rotatably supported by a bearing 64. It will be noted that there is a clearance between the upper surface of the collar 61 and the adjacent surface of the sleeve 23a.

The lower and opposed surface of the collar is engaged by a spring 24a designed similar to the spring 24 illustrated in FIGURE 1. The spring in turn is engaged at its lower surface by a nut '65 which is held against rotation by a slotted stop member 67. The stop member 67, as noted, prevents rotation of the nut 65, but will allow it to move axially of the plunger rod 16a. The nut 65 threadably engages the lower portion of the sleeve 23a so that on rotation of the sleeve by a worm wheel set 68, the sleeve is raised or lowered so as to position the plunger rod 16a and, hence, the roll gap. Pressure applied to the plunger tl'Od 16a by the piston cylinder assembly is resisted by the spring and wherein the difference between the force of the piston cylinder assembly and the rolling force is the only force that the spring, nut and sleeve are subject to and, thus, it corresponds with the features already discussed with respect to the FIGURE 1 embodiment.

While in the embodiment illustrated the cylinder force is controlled to always exceed the rolling force, i.e., F P by an amount equal to the force of .the spring 24a, it will be appreciated that in relocating the spring 24 or spring 24a so that it exerts a force in ,the same direction of the force of the cylinder instead of opposing it as in the embodiments of FIGURES 1 and 3, the cylinder force will always be less than the rolling force by an amount equal to the force of the spring; thus F P. In this case, however, the control of the force of the cylinders is still expressed by the Equation No. 6. The embodiment of FIGURE 3 will also allow the mill to be used as a pressure rolling mill, the clearance relationship in the case of the spring 24a, sleeve 23a and the plunger 16a being illustrated in the left-hand view of FIGURE 3.

As noted, the placement of the spring 24, 24a with reference to the sleeve 23, 23a and the plunger rod 16, 16a may be varied to obtain certain design advantages as dictated by the particular arrangement contemplated. FIG- URE 4 illustrates a third location of the spring 24b. In this figure there is shown a housing 70 having an opening into which there are received mounted the roll positioning mechanism constructed generally similar to the previously described embodiments. It thus includes a piston cylinder assembly 71 comprising a piston 72 to which there is connected a plunger rod 16b which extends into the window of the housing 70. Concentric with the plunger there is arranged a sleeve 23b which is threadably associated with a worm wheel set 73. The sleeve, as in the previous arrangement, is held against rotation, but permitted to move vertically. At the bottom of the sleeve there is provided an enlarged portion forming an opening into which there is received in a large bottom portion 74 of the plunger rod 16!) which at its lower end engages a breaker block assembly 76 as in the previous embodiments. An opening 77 is formed in the portion 74 of the plunger rod and a similarly formed opening 78 is formed in the two opposite sides of the enlarged portion of the sleeve 23b. Into these openings 77, 78 is inserted a spring 24b, this construction being best illustrated in FIGURE 5.

The operation of the roll positioning mechanism of the FIGURES 4 and 5 is identical to the earlier embodiments and includes all the attendant advantages, including the ability to allow the mill to be operated as a pressure rolling mill. Accordingly, the initial mill gap is set by moving the sleeve 23b which will allow or restrict movement of the plunger rod 16b, as the case may be, by virtue of the interconnection through the spring 24b. During operation the sleeve is held stationary, receiving only the difference between the rolling force and the cylinder force, while the plunger rod is moved relative to the sleeve to deflect the spring and efiect a control of the gap of the mill.

In accordance with the provisions of the patent statutes, I have explained the principle and operation of my invention and have illustrated and described what I consider to represent the best embodiment thereof. However, I desire to have it understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

What is claimed is:

1. In a rolling mill or like device having a housing for receiving a pair of cooperative rolls between which material to be rolled is passed:

roll mounting means for rotatably supporting the rolls in said housing, one mounting means being at least adjustable relative to the other so that said rolls form a variable roll gap,

a force applier adapted to urge the adjustable roll in a direction opposite the rolling force developed between the rolls,

an opening in said housing through which a portion of the force applier extends to assume a restricting relationship with the mounting means of the adjustable roll,

a member arranged in said opening concentric with the extended portion of said force applier for limiting movement thereof and thereby establishing a desired position of the adjustable roll,

means separate from said force applier for adjusting said member,

yieldable means associated with said member and constructed and arranged to allow additional movement of said adjustable roll on operation of said force applier.

2. In a rolling mill according to claim 1, including a control system comprising means for producing a signal proportionate to a change in the rolling force and means for varying the force exerted by said force applier so that the force thereof will always be equal to the algebraic sum of the rolling force and the force of said yieldable means.

3. In a rolling mill according to claim 1, comprising a first group of mill parts which includes said readily yieldable means, a second group of mill parts which includes the housing and roll mounting means and rolls, and wherein for a given elastic change of the second group of mill parts due to a change in the rolling force a corresponding elastic change will be effected in the first group of mill parts and in a direction to compensate for the elastic change of the second group thereof.

4. In a rolling mill according to claim 1, wherein said member is arranged and constructed to limit movement of the force applier and the means for adjusting said member are subject only to tl difference between the roll- FOREIGIE PATENTS ing force and the force applied by said force applier. 931,102 7/1955 Germany Referen e Cit d CHARLES W. LANHAM, Primary Examiner. UNITED STATES PATENTS v 5 A. RUDERMAN, Assistant Examiner. 3,003,374 10/1961 Smith 722 8 US. Cl. X.R.

3,345,848 10/1967 Henschker '72248 72245, 246, 248 

